1. Technical Field
This disclosure relates to compensation of aging drift in a current sense resistor.
2. Description of Related Art
A precision resistor can be used to measure current and in other applications. However, its resistance and temperature sensitivity can drift with age—up to several percent during the first years of life. This may be caused, for example, by wear on the resistor that takes place when current is passed through it, particularly large current.
Compensation for this aging drift may be needed to insure that measurements made with the resistor continue to be accurate. The change in its resistance may be measured and used as the basis for providing this compensation.
An external calibration resistor is sometimes used to assist in the measurement of this change in resistance. The precision resistor is removed from the circuit, its resistance is compared to the external calibration resistor, and compensation is provided based on any measured difference.
This calibration process, however, can interrupt normal circuit operation. It can also require an external calibration resistor to be stored and located.